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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Multipath variational transition state theory: Rate constant of the 1,4-hydrogen shift isomerization of the 2-cyclohexylethyl radical
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Multipath variational transition state theory: Rate constant of the 1,4-hydrogen shift isomerization of the 2-cyclohexylethyl radical

机译：多径变迁过渡态理论：2-环己基乙基的1，4-氢转移异构化的速率常数

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摘要

We propose a new formulation of variational transition state theory called multipath variational transition state theory (MP-VTST). We employ this new formulation to calculate the forward and reverse thermal rate constant of the 1,4-hydrogen shift isomerization of the 2-cyclohexylethyl radical in the gas phase. First, we find and optimize all the local-minimum-energy structures of the reaction, product, and transition state. Then, for the lowest-energy transition state structures, we calculate the reaction path by using multiconfiguration Shepard interpolation (MSCI) method to represent the potential energy surface, and, from this representation, we also calculate the ground-state vibrationally adiabatic potential energy curve, the reaction-path curvature vector, and the generalized free energy of activation profile. With this information, the path-averaged generalized transmission coefficients ?γ? are evaluated. Then, thermal rate constant containing the multiple-structure anharmonicity and torsional anharmonicity effects is calculated using multistructural transition state theory (MS-TST). The final MP-VTST thermal rate constant is obtained by multiplying kMS-TMS-TST by ?γ?. In these calculations, the M06 density functional is utilized to compute the energy, gradient, and Hessian at the Shepard points, and the M06-2X density functional is used to obtain the structures (conformers) of the reactant, product, and the saddle point for computing the multistructural anharmonicity factors.
机译：我们提出了一种变迁过渡状态理论的新表述，称为多径变迁过渡状态理论（MP-VTST）。我们采用这种新配方来计算气相中2-环己基乙基的1,4-氢转移异构化的正向和反向热速率常数。首先，我们找到并优化反应，产物和过渡态的所有局部最小能量结构。然后，对于能量最低的过渡态结构，我们使用多配置Shepard插值（MSCI）方法来表示势能面，从而计算出反应路径，并由此表示出基态振动绝热势能曲线。 ，反应路径曲率向量和激活曲线的广义自由能。利用该信息，路径平均的广义传输系数αγ≥。被评估。然后，使用多结构过渡态理论（MS-TST）计算包含多结构非谐和扭转非谐效应的热速率常数。最终的MP-VTST热速率常数是通过将kMS-TMS-TST乘以γγ得出的。在这些计算中，M06密度泛函用于计算Shepard点的能量，梯度和Hessian，而M06-2X密度泛函用于获取反应物，产物和鞍点的结构（构象异构体）用于计算多结构非谐因素。

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